Controlled Spin Structure in the Magnetic Phase Mixture Film

Abstract

Spin structure between magnetic phases is a crucial role for understanding of magnetic phenomena such as exchange interaction, magnetic anisotropy, interfacial exchange bias effect, spin torque and so on. Research on nanoscale of complexity spin structure provides not only considerable understanding of physical phenomena but also the feasibility of spin based devices. In this Theses, we fabricated phase mixture film with 3-dimensional internal interface structure which is composed of randomly distributed FM and AFM phases within the single layer thin film structure. We revealed novel magnetic property by exchange interaction between nano-scale of parallel FM and antiparallel AFM ordering due to spin canting within the diffuse interface area of ‘hypo-oxide state’, which is opposite behavior to generally known fact same with ferromagnetism and antiferromagnetism. Also, the improved exchange bias effect was manifested with overcoming the limitations (thickness and shape anisotropy dependence of ferromagnet layer) through 3-dimensional internal interface structure within the single layer in comparison to previous studies with layered film structure. Furthermore, we confirmed that the uniaxial alignment of AFM spins in the phase mixture film can be achieved by injecting polarized spins which is generated through inserted nonmagnetic heavy metal (platinum) while the charge current flows the film, and it was reflected in exchange bias effect. Direction reversibility and repeatability of exchange bias effect was succeeded with flowing the current of the opposite direction.